Distributed amplifiers (DAs) have been used extensively for broadband wired/wireless applications. Various techniques, examined in different technologies, have been proposed by prior work to improve distributed amplifiers' performance parameters such as gain, bandwidth (BW), and power. Multistage cells are used to improve gain, while interstage inductive peaking is employed to compensate for the bandwidth degradation due to interstage poles of the cell (see J. C. Chien and L. H. Lu, “40-Gb/s High-Gain Distributed Amplifiers With Cascaded Gain Stages in 0.18-Rm CMOS,” IEEE J. Solid-State Circuits, vol. 42, pp. 2715-2725, December 2007).
Distributed circuits are also implemented in the context of active single-to-differential conversion (i.e., active baluns). Implemented using either active or passive components, baluns are useful for various applications, such as broadband wired connectivity and high-frequency general-purpose test and measurement equipment. Active baluns offer the advantage of achieving voltage and power gain of higher than (or around) unity, as well as a higher reverse isolation over their passive counterparts.
To improve gain in distributed amplifiers and distributed circuits, multi-stage transconductance (gm) stage have been suggested. However, only the output of the last gm stage was used as an output, and the signal on the output of other stages was dissipated on the resistive load.
Accordingly, improved distributed amplifier and distributed circuits designs capable of improving the overall gain without degrading bandwidth, thereby improving the overall gain-bandwidth (GBW) and linearity are needed.